1. Field of the Invention
This invention relates to an infra red focal plane staring array which is capable of multiple applications and, more specifically, to a novel architecture for such focal plane staring arrays.
2. Brief Description of the Prior Art
Focal plane staring arrays are generally composed of a matrix of plural detector elements, each of the detector elements having an associated circuit with a capacitor which is charged in proportion to the amount of energy impinging thereon. Signals indicative of the charges on each of the capacitors in the array are read out, generally in serial manner, so that one detector element is being read out while the capacitor associated with the next detector element is being charged up. The capacitors are then again charged in accordance with the amount of energy impinging thereon and later read out. This procedure is repeated, generally on a timed basis. The outputs from the capacitors are therefore not simultaneously available or are not available in any manner such that the signals from predetermined ones of the detectors can be selected for operation on those signals only in some predetermined manner.
For advanced applications of staring focal plane arrays, multiple features are desired. For reduced data rates, the ability to "window" or output only a subarea of the focal plane array or only predetermined ones of the detectors of the focal plane array is advantageous. Multiple windowing or the ability to output upon request multiple subareas of the array is advantageous for tracking multiple targets in a large field of view. Another feature that is desirable is electronic dezoom to reduce data rates on large targets. Electronic dezoom combines adjacent detectors into one. That is, for a 2:1 dezoom, four detectors are combined into one. A 256.times.256 array becomes a 128.times.128 array. For missile seeker and other applications, it is desirable to change these features at will so that the sensor can adapt to the scenario at hand. For long wavelength infrared applications, high dynamic range is required which means large charge storage capacity for each detector is necessary. Some applications require that the signals from all detectors be integrated and simultaneously sampled to allow for accurate tracking and location of targets. This mode is typically referred to as a snapshot mode. Other applications allow the detector signals to be sampled at different times. Typically, this is performed by staggering the sampling across the array performing an electronic scan of the detectors.